In general, as a constant braking force is applied, friction brake systems tend to decelerate the vehicle more intensely when approaching a standstill than at higher speeds. This is caused by the transition from dynamic friction to static friction on the friction surfaces between brake lining and brake disk or brake cylinder. Therefore a sudden change in deceleration can be felt by the driver at the time of transition from braking to vehicle standstill.
Other forces and changes in forces act upon the driver through the oscillation of the axle suspension if the vehicle has performed a pitching motion caused by the torque during braking. Such effects also appear in known electrically controlled brake systems.
An object of the present invention is to control the brake system so that at least one of these effects felt by the vehicle occupants is reduced, even with an inexperienced driver.
SAE Paper 960991, dated February 1996, describes a brake system for a motor vehicle wherein the wheel brake pressure of the vehicle is set by actuating a valve system as a function of the braking command manifested by actuation of the brake by the driver.
European Patent No. 375 708 (corresponding to U.S. Pat. Nos. 5,129,496 and 5,209,329) describes a method for calculating vehicle deceleration at low vehicle speeds from the wheel speed signals and deriving therefrom the time when the vehicle stops by extrapolation.